Ramping up renewable energy storage
Energy storage is one of the most
pressing issues facing the renewable energy industry. AES Energy
Storage recently completed a 32 MW integrated battery-based energy
storage project at the 98 MW Laurel Mountain wind project in West
Virginia, said to be the largest battery installation attached to the
power grid in the continental United States.
Being able to storeenergy is one of the most pressing issues facing the
alternative energy industry today.
By their nature, wind and solar power are intermittent, with power
generation possible only when the wind blows or the sun shines. But if
someone is able to figure out a practical, affordable way to store
power, it would be a tremendous boost to wind and solar. It is often
referred to as the "silver bullet" that could propel renewable energy
development to a whole other level.
Clean energy storage, as it is often called, is getting a fair bit of
attention and a good deal of capital.
According to a recent Ernst & Young LLP report, U.S. venture
capital investment in cleantech companies increased by 73 percent to
$1.1 billion in the third quarter of 2011, compared to the year
Of particular note, the energy storage segment led cleantech investment
during the third quarter, raising $421 million. This segment raised a
total of $865.2 million through the first three quarters of 2011.
"We saw significant commitments in energy storage, which reflects a
growing corporate focus on proactively managing their energy mix," said
Jay Spencer, Ernst & Young LLP Americas' cleantech director.
Major power generation companies and utilities are among those
investing millions of dollars in energy storage.
Washington, D.C.-based AES Corporation, a Fortune 200 global power
company, which had revenues of $17 billion in 2010, is among the larger
power players looking to move renewable energy storage forward.
AES has set up a subsidiary company, AES Energy Storage, to be the
owner-operator of storage projects designed to improve the performance
and reliability of the power grid, utilizing patented software, dynamic
power control, and storage technology. AES Energy Storage essentially
deploys and operates projects to help utilities, power markets, and
renewable developers level the variability of generation and demand on
Among AES Energy Storage's recent projects was 32 MW of integrated
battery-based energy storage at AES Wind's 98 MW Laurel Mountain wind
project in West Virginia. The combined wind and storage system there is
providing renewable energy to the PJM Interconnection, the largest
power market in the world. PJM is responsible for keeping the lights on
in all, or part, of 13 U.S. states.
According to AES, the Laurel Mountain project is the largest battery
installation attached to the power grid in the continental United
"Energy storage technology is the silver bullet that helps resolve the
variability in power demand," said Terry Boston, PJM president and CEO.
"Combining wind and solar with storage provides the greatest benefit to
grid operations and has the potential to achieve the greatest economic
Using advanced battery technology, the storage service provided by AES
Energy Storage will help optimize the renewable energy generated at
Laurel Mountain. The project provides PJM with regulation service,
delivering instantaneous response to grid operator requests for power,
helping to match generation and demand. The storage also allows the
wind facility to control the ramp rate of its generation, smoothing out
fluctuations in minute to minute power output.
AES Laurel Mountain is among the first wind generators to supply
critical operating reserve capacity to help maintain the reliability of
the power grid, says AES.
"The Laurel Mountain project is a unique application of wind and
battery storage technology combining clean energy production with state
of the art grid support services," said Phil Herrington, president of
Global Wind Generation for AES.
"The storage facility is more than double the size of our previous
projects, demonstrating our ability to scale up this advanced power
resource," added Chris Shelton, president of AES Energy Storage.
AES Laurel Mountain consists of 61 GE 1.6 MW wind turbines capable of a
combined power generation of 97.6 MW and 32 MW of A123 Systems energy
storage devices. The 61 wind turbines are mounted on 80-meter towers
deployed along a 13-mile stretch of Laurel Mountain in Ran-dolph and
Barbour counties near Elkins, West Virginia.
Piers Lewis was project manager for AES Energy Storage on the Laurel
Mountain project, and he noted that the company has gradually scaled up
its energy storage projects over the last several years. There were
projects for California ISO and the Midwest Independent Transmission
System Operator Inc. (MISO). "Those were smaller projects, in the 1 to
2 MW range," explains Lewis. "The first larger system we did was 12 MW
in Chile, which has been working since late-2009 on the Chilean
Late in 2010, it completed the first 8MW of a planned 20 MW grid-scale
battery-based energy storage system in the New York power market. The
project is designed to deliver instantaneous response to grid operator
requests for power, helping to level the variability of generation and
demand on the grid.
The Laurel Mountain energy
storage facility was built on a one-acre site next to the substation,
below an existing transmission line, at an elevation of 2800 feet.
The Chile and New York projects, however, are standalone, while the
Laurel Mountain project ties in with a wind farm and is larger.
"We've had experience over the last four years with smaller projects,
then gained experience with the grid operations, and then moved up to a
larger application for frequency regulation and renewable integration
at Laurel Mountain," says Lewis. "We think there is big potential for
using this storage technology to provide peaking capacity on power
grids, displacing traditional peaking capacity, such as natural
Delivering power at such peak times can mean significant revenues for a
While the Laurel Mountain wind storage project is 32 MW, AES Energy
Storage is at the point that it can take on much larger projects, in 50
MW modules. The company has proposed a 400 MW battery storage peaking
capacity system for the Long Island Power Authority in New York State.
"This has been a big year for us," says Lewis. "We have a 32 MW project
built and efficiently working at the Laurel Mountain wind project, and
now we're at the stage where we can do much larger projects, on a
That could include combining efforts with additional wind power
projects in the future, as well.
While Lewis did not use the term "silver bullet" for energy storage, he
notes it can play a significant role in renewable energy projects.
"Energy storage can play a number of roles in power grids, and
renewable energy integration and facilitation of integration of
renewable energy into the grid is an important one. So we really jumped
at the opportunity to work with our colleagues at AES Wind to combine
storage with the Laurel Mountain wind project," said Lewis.
"With Renewable Portfolio Standards, there are requirements for more
renewable projects to generate energy, and energy system operators will
need better control over the variability of wind and solar to integrate
them. The fast responding energy storage projects we provide are an
excellent tool for system operators to quickly adjust system frequency,
keep everything stable, and maintain reliability on the grid."
There are several different features of energy storage systems that can
help wind power projects, says Lewis.
"As variable energy, such as wind, becomes more important, system
operators can make good use of energy storage to smooth out the
variability—but it also allows you to store wind generation power
at night, for example, when there is less demand for power, to use
during peak times.
The Laurel Mountain wind project provided an opportunity to work on a
high profile wind project not too far from the nation's capital
(Elkins, West Virginia, is only a three-hour drive from Washington) and
to work with a major system operator—PJM.
Even though Laurel Mountain is fairly close to some major towns such as
Elkins, Lewis noted the project came with its challenges. It is in a
remote area and located on top of a mountain ridge, so they had steep
inclines on construction roads and not much land to work with at the
top of the ridge. The energy storage facility was built on a one-acre
site next to the substation, below an existing transmission line, at an
elevation of 2800 feet.
Energy storage projects are new creatures for most government bodies,
so AES Energy Storage provided plenty of information on what they
wanted to do in presentations to the various government agencies, such
as the Public Service Commission of West Virginia.
"It just takes time because it is different," explained Lewis. "A
storage project is not your traditional gas-fired power plant or wind
"They carried out a rigorous review of what we proposed, how it would
work and whether there would be any environmental impact. There is no
air pollution with the AES system, we don't need any water, and there
are no water discharges—it is very benign environmentally."
The energy storage system at
the Laurel Mountain wind project is made up of a staggering 1.3 million
lithium-ion batteries enclosed in about 2,000 battery packs, which in
turn are in 16 shipping container-sized units.
The fact that the storage systems
are low maintenance and do not require any fuel or water, means that
they can be located in places where traditional power resources could
not go, making them ideal for remote wind and solar projects, he added.
Lewis explained that the lithium-ion batteries used at Laurel Mountain
were designed for hybrid buses and electric buses—the batteries
are in use in buses in New York City and Denver, among other U.S.
"They were developed for transportation applications in city
environments, so they've been studied from a permitting, environmental,
and safety impact aspect for many years." He notes that some hand
tools, such as drills, also have the same kind of batteries.
"We showed the agencies that this is not the first time these batteries
have ever been used—they are used in a number of applications
As with some of their previous projects, AES Energy Storage used
lithium-ion batteries from A123 Systems Inc. at Laurel Mountain. The
system there is made up of a staggering 1.3 million batteries enclosed
in about 2,000 battery packs, which in turn are in 16 shipping
At Laurel Mountain, these thousands of batteries allow AES to adjust
power delivery to the grid up and down, making the project less subject
to sudden drop offs in power due to changes in the wind. Separate from
the wind farm, the battery operation also sells frequency regulation
services to grid operator PJM, supplying quick bursts of power to
maintain an even balance between power supply and demand on the grid.
This, says Lewis, is where most of the revenue for the battery system
currently comes from.
"We assist PJM in providing stability and reliability, to keep the
frequency where it needs to be to help control the grid."
This, Lewis says, can be a very demanding task. "The dispatchers at PJM
are sending signals to Laurel Mountain every four seconds—the
signal might be 'charge at 20 MW'—four seconds later, the signal
might be 'discharge at 3 MW.' We can jump around with extremely fast
response times, to help system operators smooth the frequency
variations on the grid." As an example, the system at Laurel Mountain
can go from positive 32 MW to negative 32 MW in less than a second.
Related to the wind project, the system essentially helps make the
power generated from the 61 wind turbines more useful to the grid. "As
the wind comes up and drops off, the battery storage system can respond
to smooth out and ramp control the power generated from the wind."
That's very useful, considering that within an hour, power
generated from wind could go from 98 MW to zero MW at Laurel
Lewis noted the batteries are fairly low maintenance, and AES has
developed these protocols from its other operating storage projects.
"We understand maintenance for reliability of a power resource. There
are no moving parts, it involves checking the transformer oil, some
basic preventative maintenance on switches and other items, and taking
care of the storage systems. There is not a lot of additional work and
maintenance required in addition to what is already being done on the
wind farm itself."
The more complicated aspects of the system are in the sophisticated
control systems and are hard wired into each operation. AES has
developed the control technology, some of which is patented. They
develop the algorithms within each system and make any necessary
adjustments from their control center in Washington, D.C. The inverter
systems, supplied by Parker, also have sophisticated control systems.
HMT Inc., the same contractor that did the AES battery storage project
in New York State, also did the Laurel Mountain battery project.
"We've worked with them on a few projects, and they're familiar with
what we do, but there are many contractors that could do these types of
projects," says Lewis. "It's a modularized system, so it's easily
delivered, and we have layout drawings showing the locations for wiring
up and all the electrical characteristics for the contractor to tie the
containers to the grid."
Not to oversimplify the project, but AES wants the battery projects to
be, as much as possible, plug and play.
Looking ahead, Lewis and his colleagues at AES Energy Storage see great
potential for battery storage on future wind power projects. "It's very
exciting for us to be able to facilitate renewable integration with
emissions-free capacity to match emissions-free energy generation, such
as wind power."